1973-74: Rochester (Vic) Drains. Pesticide: Amitrole

State Rivers and Water Supply Commission

18 November 1979

Large quantities of the weedicide amitrole are used by the Commission, mainly to control the growth of water couchgrass in drains. The commercial product generally used, of which amitrole is the active ingredient, is Weedazol TL.

Amitrole is not used for this purpose or for the control of other aquatic species in the U.S.A. because of its alleged cancer producing properties. The evidence for this claim was considered by the Health Department (through the Interdepartmental Committee on Pesticides – the forerunner of the Pesticides Review Committee), but was rejected. As a result the proposal by the Commission to use amitrole for aquatic weed control was accepted.

In spite of the approval given to use amitrole, a common belief amogst workers in the aquatic weed field is that a move away from its use would ultimately be desirable, simply because of its controversial history. It is now considered that more positive steps should be taken with this objective in mind.

The reason for this proposal is that legal action at present being taken by the Environment Protection Authority in the U.S.A. could result in the weedicide 2,4,5-T being banned in that country. Pressure for a similar ban in Victoria is certain to follow, although it would have little immediate effect on the Commission’s weed control program as only a relatively small quantity of 2,4,5-T is used. On the other hand, the Lands Department and farmers throughout the State would be obliged to use amitrole instead of 2,4,5-T for control of some noxious weeds such as blackberry. It is only a matter of time before amitrole, when used on such a scale, would come under scrutiny and perhaps be banned.

1973/4? Testing
Drains, Rochester and Murray Valley
51    0.22ppm 220 ug/L
52    0.17ppm 170 ug/L
57    0.78ppm 780 ug/L
58    2.40ppm 2,400 ug/L
59    2.10ppm 2,100 ug/L
62    2.00ppm 2,000 ug/L